Strive for greatness and draw the chemical structure of the fo...

Question

Strive for greatness and draw the chemical structure of the following peptide: S-T-R-I-V-E.

Accepted Answer

Alright. So this practice problem wants us to strive for greatness and draw the chemical structure of the following peptide, strive. And so we're gonna follow our 3 steps for drawing a peptide. And in the first step, we're gonna draw the peptide backbone and identify alpha carbons. Now when we're drawing the peptide backbone, we know that we draw an NCC set or a nitrogen carbon carbon set for each amino acid residue that's in the peptide. And since we have a total of 6 amino acid residues in the peptide, we're going to have a total of 6 NCC sets or nitrogen carbon carbon sets. And so let's go ahead and draw that in first. So, over here we have a nitrogen and we know that we're gonna have NCC, so that's one set right there. Then we have another n c c set, that's 2. Then we have n c c, that's 3. N c c, that's 4. N c c, that's 5. And then n c c that's 6 n c c sets. And so, essentially we know that, we need to identify alpha carbons, and the alpha carbons gonna be the middle carbon within each of these, n c c sets. So here is our middle alpha carbon right here. Here's the next NCC, so it's gonna be the middle alpha carbon. NCC, middle carbon. NCC, middle carbon. NCC, middle carbon. NCC, middle carbon. And NCC, middle carbon. Alright. So now that we've got all of our middle carbons, alpha carbons labeled, we can quickly tell if we've got the right number of NCC sets if we count the number of alpha carbons. So, we have a total of 5, 6, alpha carbons, which means that we have 6 amino acid residues accounted for and the appropriate amount of NCC sets. And so, we know that at the end terminal end there's gonna be a free and ionizable amino group, so an NH 3 plus and then at the opposite end the, carboxyl end, we know that there's gonna be a free and ionizable carboxylate group. And so that is it for the first step, and in the second step we can draw in the carbonyl groups and consider amino acid chirality. And so the carbonyl groups are gonna be on all the carbons that are not labeled with the alpha carbon symbol, and so it'll be on all of these indicated carbons here. And so, that is it for the carbonyl groups. And now all we need to do is consider amino acid which is just remembering that life predominantly uses l amino acids in their proteins. And so to confirm that all of our amino acids have the l configuration, we can just remember that if the r group is going down, then it has to be on a dash. But if the r group is going up, then it has to be on a wedge. And so looking at our first amino acid alpha carbon over here, notice that it's pointing in an upward direction with these bonds here, which means that our r group is going to be going up, and when our r group is going up it's going to be on a wedge. And so up here we can draw a wedge, and then this alpha carbon is going down, so we can draw it on a dash. This one's going up, so we can put it on a wedge. This one's going down so we can put it on a dash. This one's going up so we can put it on a wedge, and this one's going down so we can put it on a dash. And that is it for step number 2. So in step number 3, all we need to do is fill in the hydrogens on the nitrogen atoms. So essentially just drawing in hydrogens at these nitrogens indicated here, and then we need to fill in the r groups for each amino acid residue. And so our first amino acid residue is s, which is for serine, and the next one is t, which is for threonine. And we know that alcohol is a serious threat, and so the serous is for serine and the threat is for threonine. So we know that serine and threonine have alcohol groups and there are groups. And so, serine is literally just alanine with an alcohol group, and alanine we know is CH 3, but we know that the number of hydrogens are going to change for serine and it's going to end up being just 2. And then it's gonna have an alcohol group branching off of it. So, that is it for serine structure and we can move on to theanine. And really, theanine structure is branching right off of serine. So, what you'll see is that we have a carbon and an Oh group coming off just like what we have over here. But with threonine structure, it has 3 different parts around its central carbon atom and its r group, and those three parts are a hydrogen, an alcohol group or a hydroxyl group, and a methyl group, a CH three group. And so that is it for the renin structure, and we can move on to our next one which is r, and that's for arginine. And we know that arginine has features of a knight sword or lysine's r group, and because knight swords we use to poke people with, we can count the number of pointy ends that the r group, that the, one letter code r here has that we could try to poke somebody with. And since it has 3 pointy ends that we could try to poke somebody with, that means that there's a 3 carbon start to our chain here. So we have a 3 carbon start, c h 2, c h 2, c h 2, and then that also reminds us that there's a triangular nitrogen structure at the end of the r group. And the way that that triangular nitrogen structure works is that there's a nitrogen, a carbon, and a nitrogen, and then the carbon is double bonded to another nitrogen. And then we fill in the hydrogen, so this one's gonna have 1, this one's gonna have 2, and then this one will also have 2, and it's gonna have a positive charge. And so that is it for arginine structure. And then, next what we have is the 'I' and the 'I' is for isoleucine, and isoleucine is an isomer of Leucine, which means it has the same chemical atoms, but just a different arrangement of those chemical atoms. And that arrangement we can get from comparing it to valine since, isoleucine is a lopsided valine. And so all we need to do is draw valine. So valine is alanine with a v shape like that, and then we make the valine lopsided by drawing an extra methyl group, and that is it for isoleucine. So then, next what we have is valine, and we know that valine is literally alanine with a v shape, so it's just gonna be c h with 2 methyl groups branching off making a v shape like that. And then last but not least, what we have is e which is for glutamic acid. And so because it has the GLUT in it, we know that it's gonna have an extra butt section and extra c h two in comparison to aspartic acid. And so all we need to do is draw in an extra CH 2 in comparison to aspartic acid, and aspartic acid is just alanine with a carboxyl group. And so we draw in CH 2, we draw in an extra CH 2, and then we draw in the carboxyl group that makes it an acid. So we know that it's glutamic acid, so it has to have a carboxylic acid. And so it's going to be ionized like this as a carboxylate group, so we have a carboxylate group here, we have an extra c h two butt section if you will, that is accounted for by the glute. And so this is glutamic acids, r group and and because it's ionized it's actually going to be glutamate. And so essentially that is it for our peptide here and we've drawn the peptide STRIDE, the chemical structure for it. So, that concludes this practice problem and I'll see you guys in our next one.

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Strive for greatness and draw the chemical structure of the following peptide: S-T-R-I-V-E.

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